The present invention relates to damping devices and more particularly, to a hydraulic damper for drawer, which buffers return stroke of the piston rod, allows quick forward stroke of the piston rod without much resistance, and absorbs shocks and reduces noises during reciprocating movement of the piston rod with the drawer.
U.S. Pat. No. 6,615,450B2 discloses an apparatus for the damping of impacts, preferably the impacts of furniture doors or drawers. According to this design, a compression spring is used to impart a damping resistance to the furniture drawer as the piston rod is moved to the inside of the cylinder. When the piston rod is extending out of the cylinder, the tube-section-like part of the compression spring is compressed to absorb shocks, lowering the noise level. However, because the compression spring has a certain length, it may cause an unsmooth movement of the piston rod.
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a hydraulic damper for drawer, which imparts a high damping resistance to the piston rod as the piston rod is moved toward the inside of the cylinder, smoothening the return stroke of the piston rod.
It is another object of the present invention to provide a hydraulic damper for drawer, which allows the piston rod to be extended out of the cylinder at a high speed without much resistance and, which absorbs chocks and reduces noises during movement of the piston rod.
It is still another object of the present invention to provide a hydraulic damper for drawer, which uses a less number of parts to achieve shock-absorbing and noise-reducing functions.
To achieve these and other objects of the present invention, the hydraulic damper comprises a cylinder holding a hydraulic fluid, a piston rod moving in and out of the cylinder and having a pin at one end inside the cylinder, a rigid valve block affixed to the inner end of the pin of the piston rod and having equiangularly spaced through holes, a retainer affixed to the outer end of the pin of the piston rod, a piston coupled to the pin of the piston rod and movable along the pin between the rigid valve block and the retainer and having a plurality of axially extending through holes, a number of the through holes of the piston being respectively aimed at the through holes of the rigid valve block for allowing the hydraulic fluid to pass through the piston in one direction at a high speed during outward stroke of the piston rod and to pass through the piston in the other direction at a low speed during inward stroke of the piston, and a shock absorber that buffers the impact of the rigid valve block when the piston rod is extended out of the cylinder. Further, a cushion block is mounted inside the cylinder near the rear cap for buffering the impact when the piston rod is extended out of the cylinder at a high speed.